A vehicle may include or have mounted thereon one or more cameras for capturing images of the environment around the vehicle. The images may be used for detecting the presence of objects, such as lanes on the road or traffic signs, or may provide the driver with a view of the immediate vicinity of the vehicle. The view of the immediate vicinity of the vehicle may be used to assist the driver when parking the vehicle or may be used to improve safety as the driver is able to view areas which are screened from him in a normal driving position. Hazards or possible hazards may also be detected from the captured image or images and then provide the driver with a warning or the information may be used in connection with driver assistance systems to actively take control of the vehicle and avoid the hazard.
Typically, several cameras, for example four, are provided on the vehicle. The images from each of the cameras may be combined to provide a 360° image in the form of a top view, also denoted as a bird's eye view, or a panoramic view. The images from adjacent cameras, for example a front camera and a side camera, may overlap with one another in order to provide an uninterrupted 360° view.
The cameras may be calibrated to determine the position and orientation of the camera relative to its surroundings. For a vehicle, the position and orientation of the camera relative to a known datum, for example the center of the front axle, may be determined in order that the images from the camera may be used to accurately combine multiple camera views into a single surround view and to accurately determine the range of an obstacle, for example.
Calibration of the cameras may be performed during manufacture of the vehicle. However, systems for calibrating the cameras automatically while the vehicle is driving have been developed to compensate for misalignment which may occur over the lifetime of the vehicle or to calibrate the position of a camera mounted on a vehicle after its manufacture. For example, DE 10 2009 057 996 A1 discloses a system for determining the position of a camera relative to the position of a vehicle. Such systems, in which a camera is calibrated while the vehicle is moving, may be denoted as online calibration systems.